Process for producing anhydrides of heterocyclic boron compounds



Unite PRO'CESS'FORPRODUCING ANHYDRI'DES: F HETEROCYCLIC BORONCOMPOUNDS Philip s. Fay, Lyndhurst, and Lorraine s. Szabo, Cleveland, Ohio, assignors" to The Standard Gil Company, Cleveland, Ohio, a corporation ofiQhio No Drawing? '-Filed SeptI9, 1957, Ser. Noi 682,637

Claims. (Cl. 260- 462) This invention'relates to organic 'boron compounds and, more particularly, to the anhydrides'of certain heterocy ates atentQ clic compounds containingboron, oxygen,-and carbon in particularly resistant to oxidation and to hydrolysis to form boric acid upon expo-sure to water, a property not possessed by the common organic esters of boric acid,

such as, for example, tertiary'butyl bo-rate. These esters are also moderately soluble in hydrocarbons, as well as f water, permitting a wider variety of uses. Neither the" anhydrides nor the esters formed therefrom result in gas-" oline-insoluble compounds upon exposure to water or moist air as do most boron compounds, and the anhydrides can be used as additives in gasoline and other hydrocarbons.

The-anhyd'rides of the invention are especially adapted for use in compositions in which it is desirable to introdu'ce boron and which may contain water. In gasoline, for example, a small amount of water is usually present as a result of Washing-the gasoline-during manufacture. 1

Upon the addition of our anhydrides to such gasoline, the anhydride may react with the Water content, but the resulting boron ester is soluble in the gasoline and provides the boron content that is desirable for promoting enhanced engine performance.

The compounds of theinvention may be defined by the following structural formula:

where R R R and R may each be hydrogen or an alkyl radical of 1 to 6 carbon atoms, preferably the methyl group, provided that not more than one of the pair of radicals R and R which are attached to the same carbon atom is hydrogen, and provided that not more than one of the pair of radicals R and R which are attached to the same carbon atom is hydrogen.

Compounds within the scope of our-invention are as follows:

It is important in accordance with *our'invention that not 'more than 'one'of the' pair of radicals R and R and not morethan one of the pair of radicals'R and R; which areattached to the same carbon atomshould be hydrogen, i.e. at least one*Of'thepairof radicals R and R is i an alkyl radical and-at least'one of the pair of radicals R and R is an alkyl radical. Unless this condition is satisfied, the compounds are not stable in the presence of moisture and hydrolyze to form boric acid which precipitates in gasoline. Forexample, when any of the butylene glycols are employed as the reactants to formcompounds in which all four of the radicals R ;'R ',"R or R are hydrogen, theco'rnpound hydrolyzes or precipitates bon'c'acid when added to moist gasoline.

Thecompou'nds of the invention may be made by react-- ing the correspondirig glycol having the formula H H '5 R1.0'-H 0 RITE aat I where R R R and R are defined as heretofore,=-with an equal molar amount of orthoboric acid (H BO The materials are reacted at mildly elevated temperatures,

and the two and one-half moles of water of reaction are removed or the product otherwise separated from the water of reaction; Boric oxide (B 0 which is the anmoval of the water," such as by blowing with air, nitrogen,

or by distillation. Allof'the water can be removed by simple boiling. However, a certain amount of the reaction product will be lost by volatilization during the re-' moval of the water. The elimination of the water is aided by blowing with a gas, although in this procedure there is still some loss of the product. For this reason, it is preferred to remove the water by fractional distillation or by azeotropic distillation, which lowers the temperature at which the water can be removed and minimizes product loss. Fractionation can also be used in the azeotropic distillation. any of the difficulties normally attributed to reactions of this type. V

The invention will be better understood in connection with the following example in which the glycol is 2- methyl, 2,4-pentanediol, i.e., a compound in which R R and R are a methyl group and R is hydrogen."

Example I 49.5 grams of dry orthoboric acid and 94.5 grams ofthe initial temperatureyat which time themixture be i came solid. The mixture was-then-heatedand' b'eCa'ine PatentedNov. 22, 1960 The reaction proceeds readily and without a zene was added and the water formed was removed azeotropically by distillation with the benzene over a period of several hours. The reaction proceeds in accordance with the following equation:

and the product may be named his-(1,1,3-trimethyltrimethyleneoxy) boric oxide. The compound of this example was found to be a colorless liquid of medium viscosity. It is miscible in hydrocarbons, and particularly in gasoline, and the common organic solvents in all proportions. It has the following additional propcities:

Boiling Point Approximately 275 C. at

atmospheric pressure and 140--142 C. at 1 mm. Hg.

"11 1.4310. Molecular weight Calculated 269.9, found 255. Percent boron Calculated 8.01, found 7.92.

was found:

Percent Calculated Found by Analysis Carbon 53. 39 53. 42 Hydrogen 8. 96 9.02 45 Boron 8.01 7. 79

The liquid anhydride product is very hydroscopic and readily reacts with water to form a white crystalline solid ester. Upon exposure of the anhydride to air, the atmospheric moisture will hydrolyze the anhydride to this solid ester, which has the following formula:

fills):

CO\ HZC/ B-OH 0-0 H CH;

and may be named 1-hydroxy, 3,3,5-trimethyl, l-bora, 2,6-dioxacyclohexane or 1,1,3-trimethyltrimethylene acid borate. The ester has a solubility of 11 grams in 100 grams of water, 58 grams in 100 grams of benzene, 156 grams in 100 grams of isopropanol, and about 2 /2 to 5 grams in 100 grams of gasoline, depending upon the composition of the latter, all as measured at 86 F.

The ester was analyzed and found to have the following composition:

While the anhydride reacts readily with water, the ester formed is resistant to hydrolysis and soluble in hydrocarbons and many organic solvents.

Example II 52 grams pentane diol-2,4 is reacted with 31 grams of dry orthoboric acid under conditions the same as that .in the previous example. The product was a clear, colorless, viscous liquid having a boiling point of 114 C. at 1 mm. Hg. It has the formula The yield was 61 grams which was vacuum distilled at 1 mm. Hg to give a yield of 55.8 grams. The compound reacts with water to give a product that is crystalline solid, having a melting point of 76 C. and which has the formula Gasoline solutions containing up to 3 cc. per gallon of tetraethyl lead and to which all of the above anhydrides had been added in an amount to provide 0.002 to 0.1% boron were stored in open beakers in a moist desiccator for several months. No crystals were formed,

and analysis of the gasoline before and after the test showed the boron content to be the same. No precipitation occurred when the samples were stored at 10 F. for several months.

A specific use of the above anhydrides will be illustrated in connection with gasoline which has been washed with water following conventional caustic treatment. To this gasoline was added 1 /2 cc. of tetraethyl lead per gallon and one theory of ethylene dibromide as a scavenging agent for the lead, together with enough of the compound of Example I to provide 0.004% boron in the above gasoline mixture. No precipitate formed.

We are aware of the fact that it has been proposed to react glycols with boric acids in which the ratio of glycol is higher, such as 3:2 or 2:1. Such reactions link carbon through oxygen to all of the boron valences and give compounds that have a lower boron content for a given glycol, a distinct disadvantage for uses where the amount of the compound required is expressed in terms of boron. These compounds do not hydrolyze readily to eliminate moisture from the compositions to which they are added; and if'they are hydrolyzed slowly, it is with the liberation of the glycol, which may be objectionable in many instances. We are not aware of the reaction of glycols with boric acid in a 1:1 molar ratio to give compounds of the formula claimed hereinafter and having the advantages described herein.

This application is a continuation-in-part of application Serial No. 554,125, filed December 20, 1955, now abandoned, which is a continuation-in-part of application Serial No. 456,614, filed September 16, 1954 (now Patent No. 2,767,069).

We claim:

1. The method of preparing compounds of the following general formula:

Where R R R and R are selected from the group consisting of hydrogen and an alkyl group having 1 to 6 carbon atoms, not more than one of the pair of radicals R and R which are attached to the same carbon atom being hydrogen and not more than one of the pair of radicals R and R, which are attached to the same carbon atom being hydrogen, which comprises reacting one mole of a glycol having the formula:

where R R R and R are selected from the group consisting of hydrogen and an alkyl group having 1 to 6 carbon atoms, not more than one of the pair of radicals R and R which are attached to the same carbon atom being hydrogen and not more than one of the pair of radicals R and R; which are attached to the same carbon atom being hydrogen, which comprises mixing one mole of orthoboric acid with one mole of a glycol having the formula:

where R R R and R are defined as above, heating the resultant mixture until liquid, and continuing heating to vaporize 2 /2 moles of water.

3. The method of preparing the compound of the following formula:

(EHQZ M H20 BOB CH2 0-0 0-0 H CH: CH;

which comprises mim'ng one mole of orthoboric acid with one mole of 2-methyl, 2,4-pentanediol, heating the resultant mixture until liquid, and continuing heating to vaporize 2 /2 moles of water.

4. The method of preparing compounds of the following general formula:

where R R R and R are selected from the group consisting of hydrogen and an alkyl group having 1 to 6 carbon atoms, not more than one of the pair of radicals R and R which are attached to the same carbon atom being hydrogen and not more than one of the pair of radicals R and R, which are attached to the same carbon atom being hydrogen, which comprises mixing one-half mole of boric oxide with one mole of a glycol having the formula:

where R R R and R are as defined above, heating the resultant mixture until liquid, and continuing heating to vaporize one mole of water.

5. The method of preparing the compound of the following formula:

which comprises mixing one-half mole of boric oxide with one mole of Z-methyl, 2,4-pentanediol, heating the resultant mixture until liquid, and continuing heating to vaporize one mole of water.

References Cited in the file of this patent Hermans: Zeitschrift fiir anorganische Chemie, vol. 142, pages 103-4 (1925).

Rippere et al.: J. Phys. Chem, vol. 47, pages 204- 34, 1943.

Honig et al.: The Van Nostrand Chemists Dictionary, D. Van Nostrand Co., Inc., New York (1953), p. 6.

UNITED STATES PA'IENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,96l 38O November 22, 1960 lip S. Fay et a1. i

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

- Column 4, lines 69 to 75, column 5, lines 24 to 30-, and column 6, lines 8 to 14., the formula should appear as shown below instead of as in the patent:

R R R R w o 2 H 0 13- 0 B CH Signed and sealed this 9 th day of May 1961.

(SEAL) Attes-t:

ERNEST w. SWIDER DAVID L. LADD Commissioner of Eaten? Attesting Officer 

1. THE METHOD OF PREPARING COMPOUNDS OF THE FOLLOWING GENERAL FORMULA: 